1. Field of the Invention
Embodiments of the present invention relate to a wireless communication system, and more particularly, to a method and apparatus for guaranteeing traffic with respect to a synchronous connection-oriented (SCO) link of a Bluetooth module when the Bluetooth module is mounted with a wireless local area network (WLAN) module.
2. Description of the Related Art
In general, a wireless local area network (WLAN) module and a Bluetooth module are included in a mobile communication device such as a smartphone. When the Bluetooth module performs communication in a 2.4 gigahertz (GHz) band and the WLAN module performs communication in the 2.4 GHz band, an overlap may occur in frequency bands between the Bluetooth module and the WLAN module. When the Bluetooth module and the WLAN module perform transmission and reception concurrently, interference may occur between the Bluetooth module and the WLAN module, which may lead to degradation in performance.
An industrial scientific medical (ISM) band may be used for a Bluetooth device. The ISM band corresponds to a band between 2400 and 2483.5 megahertz (MHz). However, to avoid interference with another device, the Bluetooth device may use a guard band spacing from the ISM band by 2 MHz in a downward direction, 3.5 MHz in an upward direction, and 79 channels (e.g. 2402+kMHz, k=0, 1, 2, . . . , 78), each having a bandwidth of 1 MHz.
The Bluetooth device may use a time division duplex (TDD) communication scheme, and each channel having the bandwidth of 1 MHz may be divided based on a time slot of 625 microseconds (μs). The time slot may be used to transmit a packet. When a length of the packet is long, the packet may be divided into a maximum of five time slots to be transmitted.
A link of the Bluetooth may be classified into a synchronous connection-oriented (SCO) link and an asynchronous connection-oriented (ACO) link. In the SCO link, data may be transmitted and received through a time slot scheduled at a predetermined time interval of 625 μs. The SCO link may be symmetric and allow a point-to-point connection between a master and a slave. An SCO data packet having been transmitted once may not be retransmitted. Thus, the SCO link may be appropriate for data transmission giving a higher priority to a time factor when compared to reliability, and be used for a voice channel in general. An SCO packet to be transmitted using the SCO link may be traffic for voice transmission. Thus, transmission and reception of the SCO packet is guaranteed to be performed at a point in time of a cycle set to guarantee the voice transmission of 64 kilobits per second (Kbps).
When the WLAN module and the Bluetooth module are included together, and a separate method or apparatus for controlling transmission and reception between the WLAN module and the Bluetooth module is not employed, the WLAN module may transmit a WLAN packet during a cycle set for SCO packet transmission and thus, the transmission and reception of the SCO packet may not be guaranteed to be performed at the point in time of the set cycle. In such a case, a voice quality may be degraded to a degree at which a user may experience an inconvenience in recognizing a voice transmitted and received in a Bluetooth device.
Accordingly, research is being conducted on avoiding mutual interference in a process of communication performed by the WLAN module and the Bluetooth module.